1. Field of the Invention
The present invention relates to an image taking apparatus such as a digital camera having a multiplex image photographing mode other than a normal mode.
2. Description of Related Art
A digital camera having a multiplex image photographing mode for obtaining a single composite image from a plurality of photographed images is known. For example, Japanese Unexamined Laid-open Patent Publication No. H10-108057 discloses a digital camera that creates a pan-focus image using multiplex images picked-up with a predetermined iris diaphragm value. According to this digital camera, a plurality of images different in focal distance and focused on the foreground, the background or the like are picked up, and then a pan-focus image focused on each of a plurality of photographic objects is created from the aforementioned plurality of images.
Furthermore, it is also known that a digital camera has a function for creating a blur-controlled image in which some photographic objects such as a foreground and a background are adjusted in blur degree.
By the way, in a conventional digital camera, multiplex image photographing for creating a pan-focus image or a blur-controlled image is performed by setting the same iris diaphragm value, exposure time, etc. as in normal photographing conditions.
Accordingly, even if it is desired to take images on certain photographing conditions suitable for multiplex image photographing, it was impossible to perform such photographing.
On the other hand, in a digital camera that can take a plurality of images in a multiplex image photographing mode, it is a premise that the acquisition of a plurality of images in the multiplex image photographing mode is performed by taking a plurality of images of the same photographic object at the same or generally the same photographing position. Accordingly, in the multiplex image photographing mode, a plurality of images of the same photographic object are taken consecutively.
However, in the actual photographing, since a slight movement of a photographic object or hand blurring may occur during the photographing, it is difficult to obtain a plurality of image data all of which are suitable for the composing process.
In a multiplex image photographing mode, in order to minimize the influence of such hand blurring, etc., it is preferable to shorten the photographing time and intervals per photographing as much as possible.
Therefore, conventionally, there have been proposed to employ a plurality of image sensors in order to simultaneously obtain a plurality of image data or to employ a high-speed system clock in order to shorten the read-out time of the image signal from an image pick-up element such as a CCD.
However, in the former method, a plurality of images are obtained simultaneously, resulting in reduced influence of the photographic object's motion and/or the hand blurring due to the time progress. However, since a plurality of image sensors are arranged, the digital camera becomes larger and the manufacturing cost increases. In the latter method, a high-speed system clock is employed, resulting in an increased manufacturing cost of the digital camera. Thus, it is hard to realize this method.